Add a protocol for keying into variables. - Githubissues

stencilproject / Stencil

Stencil is a simple and powerful template language for Swift.

https://stencil.fuller.li

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Add a protocol for keying into variables. #151

Closed jimstudt closed 6 years ago

jimstudt commented 6 years ago

On non-macOS platforms key value coding can not be used to extract values from variables. The introspection strategy works, but only for fields of the topmost class. Superclass fields are not visible. This makes any kind of hierarchical classes problematic.

This PR adds a protocol with a single function which works like the key value coding func value(key)->Any?.

The advantages are:

cross platform safe
allows the Stencil templates to use names which are different from the internal implementation names of the underlying Swift files
allow the Swift types to limit what they export to the template engine
faster than KVC or introspection

I've placed the RenderKeyed protocol above KVC or it would not be used on macOS.

ilyapuchka commented 6 years ago

@jimstudt #152 should solve superclass properties issue without need for extra protocol